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  1. #include <iostream>
  2. #include <fstream>
  3. using namespace std;
  4.  
  5. class MyFileBuf : public std::filebuf
  6. {
  7. protected:
  8.     virtual int_type sync()
  9.     {
  10.         // breakpoint here never fires
  11. std::cout << "sync" << std::endl;
  12.         return std::filebuf::sync();
  13.     };
  14.  
  15.     virtual std::streamsize xsputn( const char_type* p, std::streamsize n )
  16.     {
  17.         // breakpoint here never fires
  18. std::cout << "xsputn" << std::endl;
  19.         return std::filebuf::xsputn( p, n );
  20.     };
  21.  
  22.     virtual int_type overflow( int_type c = traits_type::eof() )
  23.     {
  24.         // breakpoint here never fires
  25. std::cout << "overflow" << std::endl;
  26.         return std::filebuf::overflow( c );
  27.     };
  28. };
  29.  
  30. class MyFileStream : public std::ostream
  31. {
  32. public:
  33.     MyFileStream() : std::ostream( 0 ) { init( &buf_ ); };
  34.     MyFileStream( const char* filename, std::ios_base::openmode mode = std::ios_base::out )
  35.         : std::ostream( 0 )
  36.     {
  37.         init( &buf_ );
  38.         this->open( filename, mode );
  39.     }
  40.  
  41.     bool is_open() const { return buf_.is_open(); };
  42.  
  43.     void close() { buf_.close(); };
  44.  
  45.     void open( const char* filename, std::ios_base::openmode mode = std::ios_base::out )
  46.     {
  47.         buf_.open( filename, mode );
  48.     };
  49.  
  50.     std::filebuf* rdbuf() { return &buf_; };
  51.  
  52. private:
  53.     MyFileBuf buf_;
  54. };
  55.  
  56. int main()
  57. {
  58.     MyFileStream fs( "test.txt" );
  59.     fs << "this is a test" << std::endl;
  60.     return 0;
  61. }
  62.  
Success #stdin #stdout 0.01s 2864KB
comments (?)
stdin
copy 
Standard input is empty
stdout
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xsputn
overflow
sync
https://ideone.com/FwmuP
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
public

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